ICF (Insulated Concrete Forms) and Energy Efficiency


I. C. F. Stands for Insulated Concrete Forms. An ICF block is an expanded polystyrene  building block with a polypropylene web inside to be able to attach interior and exterior siding.

What does an ICF home look like when it is finished? An ICF home looks like any conventional new home on the inside and on the outside.  The window sills are deeper since the walls are thicker. Very few people can tell the difference between an ICF constructed home and other types of construction.

What kind of siding can be used on ICF systems?  Virtually any exterior finish can be used within the ICF system. In fact, stucco is much more cost-effective to apply over and ICF wall because the foam is already in place.  For example: brick, stucco, Hardie siding, vinyl,  or wood would be great choices for the exterior of a home.  Interiors would be great with Drywall, plaster, tongue and groove paneling, and whatever else you can come up with!

What is the approximate R-value of an ICF wall?  A typical ICF wall with a 6 inch concrete core will have an approximate R-value of 50.  Both the inside and outside panels of 2 5/8 inch EPS foam have an R-value of 25. When combined with the thermal mass of the concrete the actual performance is much higher.

What kind of foundations can be used with ICF? Any kind of foundation can be used with an ICF wall as long as the rebar extends out of the slab or footing to connect the ICF wall to the foundation. It can even be built on pilings.  When we build, it is part of the wall system which includes the footing, stem wall and wall along with the framing, sheating, insulation and house wrap.

Do ICF walls sweat?  No they do not sweat because EPS is a poor conductor of heat and cold.  Water vapor that may be present in the structure will not condense on the walls.  The EPS is open cell and repels liquid water but allows water vapor to pass through which allows the building to breath.

Can termites eat ICF?  No. Termites do not eat the foam in ICF because it is inorganic. Termites can however  eat through wood to get their favorite food, more wood.  This is a problem in traditional woodframe structures  but is not a problem with ICF homes as the structure is made of concrete.  Needless to say termites do not eat concrete.

Is ICF more expensive to build with that traditional stick framing?  Yes. Costs vary depending on the specifics of each project but usually the project total will be 2 to 7% higher overall than with a similar traditionally framed wood house. ICF homes are so energy-efficient that the cost difference is typically recouped in energy savings.

What are the main benefits of building and ICF home? ICF homes are stronger, safer, quieter, and more energy efficient than woodframe or concrete block.  ICF walls are built with steel reinforced concrete and fire retardant expanded polystyrene foam. When compared to wood framed walls, ICF walls are far more resistant to the spread of fire and are far more likely to remain standing after.

How long does it take to build at ICF home? Any ICF home can usually be built in the same amount of time as any other type of home.

How do you protect the exposed foam between the grade and the siding? A cement-based product is applied with a trowel over fiberglass mesh which is attached to the ICF wall to give it protection from stones water and other hazards.

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